Electrolytic refining of brass



Patented Aug. l, 1933 ELECTROLYTKC REG 0]? BRASS Charles A. Rose, Qranford, N. 311, assignor to American smelting and Refining Company, New York, N. K, a Corporation of New Jersey No Drawing. Application January 2, 1931 Serial No. 418,158

3 Claims.

This invention relates to an electrolytic process for treating scrap brass.

The invention provides a simple and dependable process for efficiently treating scrap brass, such as automobile radiators, for the recovery of copper and zinc therefrom in substantially pure form. The process may be continuously carried out and is capable of recovering the above named elements without the formation of substantial amounts of by-products.

The invention further consists in the new and novel features of operation and the new and original arrangements and combinations of steps in the process hereinafter described and more particularly set forth in the claims.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in claims appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of its organization may be better understood by referring to the following description in which a particular commercial embodiment thereof is disclosed. It will be understood, however, that the processes and the steps thereof may be modified in various respects without departing from the broad spirit and scope of the invention.

In the following description and in the claims the various steps in the process and the details comprising the invention will be identified by specific names for convenience but they are intended to be as generic in their applica-' tion as the art will permit.

In accordance with the present invention the scrap brass is cast into anodes which are electrolyzed in a sulphate solution containing a given percentage 'of copper and zinc and free sulphuric acid for the deposition of a substantial portion of the copper on the cathode. During this deposition the copper content of the electrolyte is held constant by the addition of suit able quantities of copper oxide.

The copper deposition is carried out until the zinc content of the electrolyte increases to a predetermined amount, after which the electrolyte is withdrawn and applied to a second electrolytic cell. Brass anodes are used in this second cell and the deposition of copper is continued until the zinc content increases to a further predetermined amount.

The electrolyte is then applied to a third cell in which the copper is substantially completely removed, the electrolysis being carried out with lead anodes. In this cell the zinc content IG- mains constant and the copper content of the electrolyte is depleted.

The electrolyte from this cell is purified in any suitable manner and is then applied to a cell using lead anodes in which the zinc is deposited. When the zinc content of the electrolyte has been depleted to a predetermined value, the electrolyte is then withdrawn from this cell and recirculated to the first mentioned cell in which copper is being deposited.

As a specific example of a method of carrying on this process, it may be noted that all of the scrap brass is cast into anodes. A portion of these anodes is used for the deposition of copper in the first section of the tankhouse, which may be called the commercial copper section.

For this purpose an electrolyte containing approximately 20 grams per liter copper and not over grams per liter zinc is employed. As the electrolysis is carried on the copper content of the electrolyte becomes depleted, due to the zinc which is dissolved from the brass anodes and is not deposited out at the cathodes. An amount of copper is deposited at the cathodes which is equivalent to the copper and zinc which are dissolved from the anodes.

. It is desirable to maintain the copper content of the electrolyte substantially constant and this is accomplished by circulating the electrolyte through a leaching tank containing a copper oxide. The amount of copper dissolved will approximately equal the zinc dissolved at the anodes plus the copper in the electrolyte which is withdrawn from the tank for the purpose to be described.

With the plant operating in the above manner the copper content of the electrolyte is maintained constant and the zinc content gradually increases as zinc is dissolved from the anodes. A sufficient quantity of electrolyte is continuously withdrawn to prevent the zinc content from exceeding a predetermined value, such. as 80 grams per liter. This electrolyte is applied to a second portion of the tank-house which may be called the stripping section. In this section it -is further electrolyzed with brass anodes until the zinc content increases to approximately 100 grams per liter. The, cathodes produced in this section, if sufficiently pure, may be melted up together with the cathodes from the commercial copper section to provide the copper outlet for the process. If they are not sufliciently pure, they may be further refined.

\ The electrolyte is then withdrawn to cells having insoluble anodes, preferably lead anodes, in

' above described.

The electrolyte is then purified in any well known manner, as, for example, by the addition of finely divided zinc, after which it is taken to a third section of the tankhouse which may be called the commercial zinc section. In this section it is electrolyzed with lead anodes until the zinc content of the electrolyte is decreased to about grams per liter, the cathodes forming the zinc outlet for the system. The electrolyte is then returned to the commercial copper section and used for the treatment of further quantities of brass'anodes in the manner above described. I

In applying the above process to a commercial plant with a. daily capacity for treating a quantity of scrap brass containing 180 tons of copper and 60 tons of zinc there will be deposited in the commercial copper section approximately 160 tons per day commercial cathodes. In the stripping section there will be deposited approximately 20 tons of commercial cathodes and approximately 60 tons of finely divided copper which will be roasted to oxide form and returned to the commercial copper tankhouse. The commercial zinc section would deposit the 60 tons per day of zinc coming into the plant.

It is obvious that the slimes formed in the above process may be treated in any suitable manner for the recovery of the metal values therefrom. The sulphuric acid content of the various electrolytes is not depleted and it will be only necessary to add sufiicient acid to compensate for losses and that which combines with the impurities to form sulphates.

It is to be noted that the above described process is substantially continuous and provides for the recovery of commercially pure copper and zinc from. scrap brass. Since the necessity for smelting furnaces is avoided, the plant cost is reduced to a minimum and an efficient and dependable process is obtained.

Although certain novel features of the invention have been shown and described and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes in the several steps of the process and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. An electrolytic process for treating brass which comprises forming said brass into anodes, electrolyzing said anodes in an electrolyte of sulphuric acid whereby copper is deposited on the cathode and the zinc content of the electrolyte increases, maintaining the copper content of the electrolyte substantially constant by circulating said electrolyte over a quantity of copper oxide, continuously withdrawing suflicient electrolyte to maintain, the zinc content below a predetermined value, removing the copper in the portion so Withdrawn by electrolysis and electrolyzing the copper-free electrolyte with insoluble anodes to deposit zinc therefrom.

2. The process for treating alloys of copper and zinc for the recovery of the metals therefrom which comprises forming said alloy into anodes, electrolyzing said anodes in a copper sulphate electrolyte to deposit the copper therefrom, maintaining the copper content of the electrolyte substantially constant and continuously removing a portion of the electrolyte sufiicient to prevent the zinc from building up above a predetermined value, electrolyzing the portion so removed with further quantities of said anodes to deplete the copper content of the electrolyte and further build the zinc content,

then electrolyzing said electrolyte with inert anodes to substantially completely deplete the copper content, purifying said electrolyte and electrolyzing with lead anodes to deposit the zinc therefrom until the zinc content is reducedto a predetermined value, then recirculating said electrolyte for the electrolytic deposition of copper in the step first above mentioned.

3.. An electrolytic process for treating scrap brass which comprises casting said brass into anodes, electrolyzing said anodes in a sulphate solution containing approximately 20 grams of copper per liter to deposit copper therefrom, continuously circulating the electrolyte over copper oxide in quantities sufficient to maintain the copper content thereof substantially constant, continuously withdrawing a portion of said electrolyte sufiicient to prevent the zinc content from exceeding approximately grams per liter, electrolyzing the portion so withdrawn with said brass anodes to deplete the copper content and to cause the zinc content to build up to approximately grams per liter, then electrolyzing said electrolyte with lead anodes to substantially remove the copper, purifying said electrolyte with zinc and electrolyzing with lead anodes to deposit zinc therefrom until the zinc content is reduced to approximately 40 grams per liter, then recirculating said electrolyte for the deposition of copper in the step first above mentioned.

CHARLES A. ROSE. 

